Dual-band antenna systems may be utilized for simultaneous transmission and reception of RF signals over two widely separated frequency bands at 20 GHz and 30 GHz. For example, an Advanced Extremely High Frequency satellite transmits at 20 GHz and receives at 45 GHz, and a Wideband Gap-filler. Satellite transmits at 20 GHz and receives at 30 GHz. However, these systems are taxed because amounts of information are continually increasing at an exponential rate. Additionally, existing single beam antennas use corrugated horns to extend the frequency of operation to approximately 45 GHz. However, for multiple beam applications, the corrugated horn is simply not suitable for satellite applications due to the thick walls needed to support the corrugations and thereby causing significantly lower RF performance and increased mass. Therefore, a smooth-wall horn that could operate simultaneously at the three frequency bands of 20 GHz, 30 GHz, and 45 GHz is highly desirable for satellites requiring multiple beams, including military satellites.